Liquid-cooled cylinder head



June 14, 1955 K. MAYBACH LIQUID-COOLED CYLINDER HEAD 2 Sheets-Sheet 1 Filed May 18, 1951 IIIIIIIIII ATTORNEY 2 Sheets-Sheet 2 INVENTOR fl/QPA MAO 5,90,

ATTORNEY K. MAYBACH June 14, 1955 LIQUID-COOLED CYLINDER HEAD Filed May 18, 1951 United States Patent LIQUID-COOLED CYLINDER HEAD Karl Maybach, Friedrichshafen (Bodensee), Germany Application May 18, 1951, Serial No. 227,060

Claims priority, application Germany September 9, 1950 4 Claims. (Cl. 123-41.76)

This invention relates to cylinder heads for internal combustion engines and more particularly to the liquidcooled type of heads adapted for use in high duty motor vehicle engines.

The invention quite especially concerns improvements in engines of this type having vertically moving intake and exhaust valves, one object being to materially irnprove the cooling of the particularly sensitive parts of a cylinder head such as the seats of the exhaust valves.

A cylinder head according to this invention enables cylinders of greater diameter than hitherto possible to be provided in high speed engines. It allows such head to be hot-cooled without impairing the reliability of service and results in a material increase of performance of the engine.

In a cylinder head according to the invention at least five valves are provided and the gas ducts comprising the valve seats are so designed that near these seats the walls are not combined or in contact with the outer walls of the cylinder head and therefore are directly contacted all around by the cooling liquid. This liquid is so directed by means of walls, partitions or other guiding members that on entering the head it first of all surrounds at a high velocity the exhaust conduits near the valve seats. For the invention is based on the conception that whenever more than four valves, for instance three intake and two exhaust valves or three intake and three exhaust valves are provided in the head, the exhaust valves, spark plugs, fuel nozzles, the exhaust conduits and other parts near a combustion chamber and between the valves should be cooled with particular efiiciency and therefore can carry a high thermic load whereby the performance and the reliability of service of the engine are increased. In addition the thickness of the walls near the valve seats of a cylinder head according to this invention can be produced with a tolerance of about 1 mm..

In cylinder head castings as hitherto produced no such tolerance could be obtained.

In the new cylinder head the cooling liquid enters through apertures below the individual exhaust conduits. v

The valves are so arranged in a well known manner that they project only little or not at all from the bottom face of the head and the engine piston can therefore move close to this bottom face of the head if this should be necessary owing to a high compression or the provision of a large combustion chamber in the head or in the engine piston.

When an equal number of intake and exhaust valves are provided in the head, it is preferably designed symmetrically to the engine axis, which means that the valves, the conduits and the means of fixation of the head on the cylinder are arranged symmetrically to a plane extending vertically along the engine axis. Therefore in such a case only a single pattern and finished model suitable for all kinds of rows and only a single kind of spare parts are required. The head can preferably be fixed to this cylinder by means of six or eight expansion screw bolts which are arranged symmetrically to the transversal axis of the head and equally or almost equally spaced from each other, whereby to guarantee a favorable transmission of pressure by supporting walls provided for this purpose and thereby a uniform and reliable packing. In order not to expose the bolts which extend across the interior of the cylinder head, to heating by the exhaust gases, the parts of the cylinder'head directly surrounding these bolts are so arranged as to be separated, as far as heat transmission is concerned, from the exhaust conduits.

In the drawings affixed to this specification and forming part thereof two embodiments of this invention are illustrated diagrammatically by way of example.

In the drawings:

Fig. 1 is an axial section of a carburetor engine with three intake and two exhaust valves on the line EF in Fig. 2, while Fig. 2 illustrates two horizontal sections on the lines AB and CD, respectively, in Fig. 1.

Figs. 3 and 4 illustrate a cylinder head for an engine operated with solid injection,

Fig. 3 being an axial section on the line GH in Fig. 4, three intake and three exhaust valves being present, while Fig. 4 shows two sections, one taken on the line JK and the other on the line LM in Fig. 3.

Referring to the drawings and first to Figs. 1 and 2, 1 is a spark plug and 2, 3, 4, 5 and 6 are five valves surrounding the plug. The valve discs do not project below the bottom face of the head. 2 and 3 are the exhaust valves, 4, 5 and 6 the intake valves. 7 is the bot: tom, 8 the top wall, 9 and 10 are the end walls and 11 and 12 the side walls of the head. From the seats of the valves 2 and 3 conduits 13, 14 lead to apertures in the side wall 11 and similar conduits 15, 16v and 17 lead from the seats of the valves 4, 5 and 6, respectively, to apertures in the side wall 12. In these side walls air exhausting plugs 18 are provided which may be opened when filling the cylinder head. In the bottom wall 7 apertures 19, 20, 21 and 22 are provided below the conduits.

Within the cavity of the cylinder head two partitions 23 and 24 are provided which extend from the bottom wall 7 7 up to the top wall 8 and enclose between them an apiii) proximately cylindrical compartment. These partitions serve for guiding the cooling water. Near the bottom wall 7 underneath the conduits 13-17 apertures 2529 are provided and similar apertures 130 are arranged directly below the top wall 0 (Fig. 1). The partition 23 forces the cooling liquid to pass for the greater part through the apertures 25 and 26 and to cool first of'all the faces 50 around the seats of the exhaust valves 2 and 3, to then contact the seats of the intake valves 4, 5 and 6, thereafter the liquid traverses the partition 24 through apertures 27, 28 and 29 and finally escapes from the cylinder head through apertures 20, 21 and 22 or other apertures provided for this purpose.

The partitions 23 and 24 are arranged as far as possible in such manner as to extend above the packing ring 43 arranged between the cylinder and its head. This arrangement provides that on the screw bolts fixing the head of the cylinder being tightened, their pressure is transmitted uniformly to the packing ring so that any deformation of the cylinder head is avoided.

42 is the cylinder liner, 44 is the top of the crankcase and 45 are packings for the cooling liquid, where it passes to and from the cylinder head. 30, 31, 32 and 33 are the four screw bolts extending through the head and four more screw bolts (not shown) extend through the grooves 34, 35, 36 and 37, these screws also serving for fixing adjoining cylinder heads. The bolts and 31 Patented June 14, 1955 ate surrounded by sleeves 38 and 39, respectively, pressed into the cylinder head and the bolts thus surrounded are cooled throughout their length and are not exposed tojheat transmission from the exhaust conduits. On the intake, side eyes may be provided in the casting of the head for the passage of bolts 32 and 33, these eyes joining the wall 12 or also the conduits 15, 16 and 17. On the exhaust side no such eyes are provided in the casting, since on that side an undesirable and injurious heating of the bolts through the exhaust conduits might su f46 is a central cavity extending between the top and bpttomwalls 7 and 8, in which the spark plug 1 and its cable are mounted.

in the embodiment shown in Figs. 3 and 4 an injection nozzle 5]. is arranged in the center of the head and around this nozzle are arranged three intake valves 5'2, 53 and 54 and three exhaust valves 55, S6 and 57. On thc yvhole the design of the cylinder head resembles that of the embodiment shown in Figs. 1 and 2. 58 is the bottom wan, 59 the top Wall, 60 and 61 the end walls and 62 and 63 the walls. 64 and 65 are intake conduits, 66 and 67 exhaust conduits. The cooling water enters through apertures 68, 69 and 70 and escapes from the head through apertures 71, 72 and 73.

75 and 76 are the partitions extending through the ipt erioreof the cylinder head. Their apertures 77-82 serve the same purpose as the apertures in the partitions 23 and 24 shown in Fig. 2. Here also these partitions extend on top of the liner packing and serve for uniformly transmitting pressure when the head is fixed on the cylinder block 86.

YA partition 87 extending in spaced parallel relation to the bottom wall 58 is arranged between the end wall 61 and the intake and exhaust conduits. They force in a stillmore efiicient way than in Figs. 1 and 2, the main current of cooling liquid to flow at high velocity around tlie bottom'part of the cylinder head and quite especially the'co oling faces 50 of the valve seats. 83 indicates the thickness'of the bottom wall near the seats of the exhaust "v'alves Owing to the favorable position of the cores provided according to Figs. 3 -and 4, these wall sections can be produced with a tolerance of about 1 mm. which cannot be obtained in cylinder heads as hitherto designed for the larger type of vehicle engines.

91 is an aperture in the top wall 59 of the cylinder head and 22 is a'plate closing this aperture, this plate being lfgrnied with a'bore 94. On the threaded section of its hub 93 a screw cap 96 is mounted which forces the flange j9 7of the injection nozzle 98 by means of apacking 99 against the hub 93. 100 are screw bolts serving for fixing the plate 92 on the cylinder head. The nozzle 98 further carries a flange 101 which is pressed by means of a packing'1 02 against the neck 103 formed in the wall 58. This ert canbe machined exactly, being accessible for tools introduced from above through the aperture 91. 105 is a compartment above the partition 87, its crosssection area of passage being so dimensioned that here "also the cooling water flows at a materially lower velocity than near the exhaust valve seats.

The invention as described and illustrated hereabove offers particular advantages for cylinders of large diameters, for instance -180 nuns. Hitherto for reasons mainly connected with the efiicient cooling of the piston such cylinders could not be employed in high speedvehiclc engines. Owing to the efiicient cooling, quiteespecially of the exhaust valve seats, according to this invention, a cylinder head as here describedpossesses an extraordinary long life such as cannot'even be obtained by interchangeable valve seats which in view of the tensions arising in tlieir use and in view of the insulating effect they produce between the seats and the cooling medium produce great difficulties. The cross-sectional areas of the cooling spaces situated behind the exhaust valve seats in the direction of flow of the cooling medium are so dimensioned that the sections from laterally acting forces.

velocity of flow of the cooling medium is materially higher at the exhaust valve seats than at all other cooling surfaces of the cylinder head.

The partitions provided for a transmission of pres sure between the top and bottom walls of the cylinder head and extending mainly above the packing ring arranged between the cylinder liner and the head in approximately parallel relation tothe cylinder axis provide a particularly favorable support for these walls and relieve the cylinder The packing between the cylinder head and the cylinder liner is particularly well cooled owing to the uniform thickness of the bottomwall of the head which is determined exclusively by the load acting thereon. These partitions may also serve for guiding the cooling liquid towards the valve seats.

The aperture provided in the top wall of the cylinder head enables the Walls surrounding the seat of the injection nozzle or the spark plug to be machined, whereby an increased cooling effect is obtained for the spark 'plug or injection nozzle. Hereby the many difiicultie's hitherto caused by an overheating of these parts are avoided and the difiiculties opposing themselves to the use of hot cooling are done away with. The walls can be machined down to a thickness which is merely subject to considerations of strength. At the same time a particularly favorable location of the cores and a uniform shaping of the walls is rendered possible, whereby difliculties hitherto arising in the production of the castings are avoided.

Cylinder heads according to this invention are particularly suitable for hot cooling by means of oil and temperatures of 140 C. and even higher can be used without any drawback. Quite particularly in such a case the increased cooling effect obtained near the exhaust valve seats and the reduced cooling effect at the other parts of the head are of particular value.

I wish it to be understood that I do not desire to be limited to the details hereabove described and shown in the drawings, for obvious modifications will occur to a person skilled in the art.

I claim:

'1. Liquid-cooled cylinder head for internal combustion engines -comprisingin combination, a hollow cylinder head body, at least fiv'e valves in head suspended within said body, valve seats formed in said body in register with each -of said valves, separate intake and exhaust conduits extending between said valve seats and'the outer body wall, the outer surfaces of the walls delimiting said conduits being fr eely accessible for cooling liquid aroundsaid valve seats, a'nd separate partitions extending between opposite sides of said body wall and formed with separate "passages for the cooling liquid for each valve facing said delimiting walls so as to conduct the main portion of the cooling-liquid entering the head directly into contact with the outer surfaces of said delimiting walls.

2. Liquid-cooled cylinder li'eadfor internal combustion engines'cornprisin'g in combination, a hollow cylinder head body, at least five valves in head suspended within said body, valve seats formed in said body in register with said valves, intake and exhaust conduits extending between said valve seats and the outer body Wall, the outer surfaces of the walls delimiting said conduits being freely accessible for cooling liquid around said valve seats, and separate structural means extending between opposite sides of said body wall and formed with passages for the cooling liquid-facing said delimiting walls so as to'conduct the'main portion of the cooling liquid entering the head directly into contact with the outer surfaces of said delimiting walls, the cross-sectional area of the inner space to the-rearof-said exhaust valves in the direction of flow of the cooling liquid being so dimensioned that the 'fiow of "cooling liquid near the other cooling surfaces is 'materiallylower than near said exhaust valve seats.

cylinder head body on said cylinder, at least five valves in head suspended within said body, valve seats formed in said body in register with each of said valves, separate intake and exhaust conduits extending between said valve seats and the outer body wall, the outer surfaces of the walls delimiting said conduits being freely accessible for cooling liquid around said valve seats, and separate partitions extending between the upper and the lower walls of said body and formed with separate passages for the cooling liquid for each valve facing said delimiting walls so as to conduct the main portion of the cooling liquid entering the head directly into contact with the outer surfaces of said delimiting walls, said head being formed with liquid admitting openings underneath said exhaust conduits.

4. Liquid-cooled cylinder head for internal combustion engines comprising in combination, a hollow cylinder head body, at least five valves suspended within said body, valve seats formed in said body in register with said valves, intake and exhaust conduits extending between said valve seats and the outer body wall, the outer surfaces of the walls delimiting said conduits being freely accessible for cooling liquid around said valve seats, and structural means extending between opposite sides of said body wall and formed with passages for the cooling liquid facing said delimiting walls so as to conduct the main portion of the cooling liquid entering the head di- References Cited in the file of this patent UNITED STATES PATENTS 1,479,129 Feilner Jan. 1, 1924 1,609,149 Wilkinson Nov. 30, 1926 1,621,521 Cappa Mar. 22, 1927 2,322,961 Yingling June 29, 1943 FOREIGN PATENTS 130,698 Great Britain Aug. 14, 1919 192,954 Great Britain Feb. 15, 1923 464,505 Germany Aug. 18, 1928 

